1. Field of the Invention
The invention relates to a bolometric focal plane array and more particularly to a bolometric focal plane array having an integrated signal processor for processing signals from an array of bolometer detectors.
2. Discussion of the Related Art
Thermal radiation detectors that operate at room temperature have been known for more than 100 years. Recently, the availability of integrated circuit and micromachining technology has revived interest in this field. It is now practical to manufacture an array containing many thousands of these detectors along with signal processing electronics.
A bolometer is a thermal radiation detector that operates by first absorbing incident electromagnetic radiation and converting the absorbed energy into heat. The resulting temperature change of the detector is then sensed by measuring its resistance, which is a function of temperature. In a large array of such detectors, it is practical to measure the resistance of only a few detectors at any given time without compromising the signal to noise ratio of the system. The signal to noise ratio is a very important parameter for practical systems.
As a result, there remains the problem of how to implement circuitry to measure the resistance of many thousands, for example more than 80,000 detectors, within the size, power, and component restrictions placed upon an integrated circuit. The integrated circuitry must measure the resistance of each element of the array and format the results into a single data stream. The signal from each bolometer far exceeds the integrating capacity of a single practically sized integrated capacitor. It is therefor a motive of the invention to provide a bolometric focal plane array with an integrated signal processor that fits within a reasonable area, uses only the components available within the integrated circuit process, and dissipates a limited amount of power.